NetWorkdays

Description of formula:
Counts work days between two days, holidays can be excluded

Syntax:
NETWORKDAYS(from, to, [holidays])

Parameters:

from(type:date)

From date

to(type:date)

To date

holidays(type:date)(optional argument)

Array of dates that are holidays and should be excluded from calculation

Returned type:

Number

Examples:
=networkdays(date(2016,1,1), date(2017,1,1))
=networkdays(date(2016,1,1), date(2017,1,1), A1:A6)